ABB Relion REG670, Applications Manual

Page: 276 / 780

Simplified, the example can be shown as a triangle, see figure 139 .
ZA
ZB
Zload
R
X
en07000016.vsd
IEC07000016 V1 EN
Figure 139: Simplified figure to derive StartAngle
0 0
32 52
arctan arctan arctan + arctan = 21.8 + 33.0 55
80 80
³ = »
ZB ZA
angleStart +
Zload Zload
EQUATION1968 V2 EN
(Equation 158)
In case of minor damped oscillations at normal operation we do not want the
protection to start. Therefore we set the start angle with large margin.
Set StartAngle to 110°
For the TripAngle it is recommended to set this parameter to 90° to assure limited
stress for the circuit breaker.
In a power system it is desirable to split the system into predefined parts in case of pole
slip. The protection is therefore situated at lines where this predefined split shall take
place.
Normally the N1Limit is set to 1 so that the line will be tripped at the first pole slip.
If the line shall be tripped at all pole slip situations also the parameter N2Limit is set
to 1. In other cases a larger number is recommended.
Section 8
1MRK 502 071-UEN -
Impedance protection
270 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual